Composition for cleaning metals



Patented May 22, 1951 CODIPOSITION FOR CLEANING METALS John P. Burke, Chicago, Ill., assignor to Birco Chemical Corporation, Chicago, 111., a corporation of Illinois No Drawing. Application October 16, 1948, Serial No. 55,007

4 Claims. 1 This invention relates to a composition for cleaning metals and has to do more particularly with a composition for removing foreign matter such as oxides, scale and the like from the surface of the metal in' preparation for soldering, welding or painting.

An object of the present invention is to provide a new and improved composition of the foregoing character.

Another object is to provide a composition of the foregoing character which is simple and inexpensive to prepare, which may be used Without special apparatus or equipment, and which is not injurious to the health and safety of the user.

Another object is to provide a cleaning composition of a pasty or gelatinous nature which may be readily applied to the surface to be cleaned, which will firmly adhere to the surface until removed, to permit the cleaning action to take place, and which may be readily removed as by washing or wiping.

Another object is to provide a cleaning composition which will rapidly and effectively remove oxides, scale and other foreign matter from metal surfaces and will provide a surface which may be painted, soldered or welded, without further preparatory treatment.

Another object is to provide a cleaning material capable of removing oxides, scale and other foreign matter from metal surfaces and which at the same time inhibits oxidation of the cleaned metal surface.

Another object is to provide a cleaning material capable of removing oxides, scale and other foreign matter from metal surfaces and which at the same time promotes increased adherence of paint or other surface coating material which is to be applied to the cleanedmetal surface.

Another object is to provide a composition capable of removing oxides, scale and other foreign matter from metal surfaces for preparing the surface for painting, soldering or welding and which composition may also be employed for removing foreign matter, such as oxides or scale, from plated metal surfaces.

Other objects and advantages will appear from the following description.

In accordance with the present invention, the cleaning composition takes the form of a pastelike material in which is incorporated an active mineral acid, or mixture of acids, capable of removing oxides, scale, as for example, welding flux residue, and other adherent foreign materials, from metal, the acid component of the composition being in excess, in a free state, and

in condition to attack and loosen the adherent oxides, scale and the like. The composition is sufficiently viscous and adherent so that it may be applied to all metal surfaces such as vertical, curved, bottom and the like, and will adhere to such surfaces until removed, so that the acid is maintained in contact with the surface for a sufficiently long period of time to exert the necessary action on any oxides and scale Which may be present.

The composition is prepared in the form of a gel of about the same consistency of the common gelatinous desserts. To this end I employ a gel which includes a water soluble silicate of sodium or potassium and I prefer to use a commercial sodium silicate known as grade 40 or waterglass and having the approximate composition lNazO-3.2SiO2. The silicate is mixed with sufficient water and With acid, as hereinafter described, to provide a gel of the desired consistency, (stiffness or hardness) and I have found that a Water solution consisting of approximately around 2% to around 10% of silicate gives the best results. It will be understood that silicate having a higher alkali content and lesser silicate content may be used but it is then necessary to employ a higher percentage of acid in order to provide effective neutralization of the alkali.

The acid component may consist of one or more of the common mineral acids capable of removing oxides and scale and at the same time one which may be carried by the silicate gel. Preferably a strong acid is employed as for example hydrochloric, nitric or sulphuric acid. While one or more of the strong acids is employed for removing oxides and scale, I also prefer to include as a small percentage of the acid component, phosphoric acid as this material has been found to inhibit rusting of the clean metal surface and, in addition, provides a marked bonding action for paint or like surface coatings, when such are to be applied to the metal surface after cleaning.

Cleaned surfaces of many metals and especially ferrous metals are subject to rapid rusting, and it is desirable in such cases to inhibit the rusting of such surfaces so that they will remain free of rust for a sufficiently long period to permit subsequent painting, soldering, or welding. Busting may be prevented by forming a thin protective coating such as a plating of a non-rusting material on the metal and I accomplish this by incorporating in my composition a suitable water soluble metallic salt of an acid from an aqueous solution of which salt the metal may be displaced by electrodeposition. Since in its preferred emacid is included in the composition, phosphatization takes place but this does not interfere with the deposition of the metal film on the base metal. The metal surface will be phosphatized only in those portions where it is not fully protected by the metal film.

In order to delay the drying of the composition and to provide a longer period of activity of the active materials which are incorporated in the gel, a small quantity of glycerine preferably is incorporated in the composition.

In preparing the composition, I have found it preferable to first dissolve the copper sulfate, or equivalent material, in water and add it to a mixture of the strong mineral acid and phosphoric acid, whereafter the silicate is added to the mixture and the mixture stirred to thoroughly mix the ingredients. Where glycerine is included, it preferably is mixed with the salt solution prior to the addition of the silicate. When the compound is prepared in accordance with the formula given hereinafter, the gel will set in about hour and the composition is then ready for use or for storing or shipping. In this connection, the composition, after gelling, is essentially solid and may be shipped without the usual precautions required in handling liquid acid materials. However, I prefer to package the composition in leakproof containers which are not attacked by the acids in the composition, such as glass jars.

In the preferred embodiment of the invention, the composition includes the following ingredients, the parts hereinafter set forth being by volume, and both the preferred proportions and the preferred range of proportions being given:

The composition prepared as above described may be employed without any preliminary conditioning of the composition or preparatory treatment of the metal surface to be cleaned. The composition is applied to the metal surface in a suitable and convenient manner as for example by spreading it thereon with a brush. The composition is allowed to remain on the surface for a sufficient length of time for the acid or acids to loosen all of the oxides and scale which period may be determined by experience or, if desired, some of the composition may be removed and the surface inspected. Should the composition adhering to the metal surface dry before it has accomplished the complete loosening of the oxides or scale, it may be moistened with water and allowed to stand for a further period. When the cleaning action has been completed, the composi- 4 tion may be removed by wiping off with a wet cloth or by washing off with water and it is not necessary to use any mechanical means such as an abrasive, or any solvent for removing either the composition or the loosened oxides andscale.

The composition of the present invention is particularly applicable to the field of automobile body and fender repair although as will be understood it is equally applicable to many other fields.

For example, it may be employed in cleaning metal fences, structural metal, stoves and innumerable other metal objects. In the use of the composition in cleaning automobile body and fender surfaces for repainting, as well as in cleaning other objects, the composition is particularly efiective inasmuch as it may be applied quickly and easily and then allowed to stand while the cleaning action takes place without attention on the part of the workman. The composition penetrates all crevices including the deepest recessses of the body and fenders and removes oxides and scale therefrom but removes only a minimum of the clean metal. Moreover, the composition does not injure the beading or adjacent painted areas as is the case where grinding or sandblasting operations are employed for cleaning the metal surfaces of the body and fenders.

The metal surface after cleaning with my composition is clean and bright and is provided with a metallic coating which inhibits the formation of rust. Moreover, the surface is slightly etched or roughened and will retain paint or other surface coatings With a high degree of effectiveness. In addition, the phosphatizing of the metal surface provides additional adherence of the paint or surface coating. The surface of the metal is not only in condition for the application of paint or other surface coating but where desired may be soldered or welded Without further preliminary treatment.

The composition of my invention also is well adapted for removing tarnish or oxide film from plated surfaces such as chromium plated trim and bumpers on automobiles. In such case, of course, the composition is applied for only brief intervals so that it removes only the tarnish and oxide films and does not attack the plating.

I claim:

1. A cleaning material for removing oxides, scale and the like from metal surfaces formed by adding, with stirring, from around 25 to around 45 parts by volume of approximately 10% aqueous solution of sodium silicate to a mixture consisting essentially of an aqueous solution of from around to around parts by volume of hydrochloric acid (specific gravity 1.19), from around 2 to around 10 parts by volume of phosphoric acid (aqueous solution, strength by weight), and from around 2 to around 10 parts by volume of copper sulfate (aqueous solution, 25 strength by weight) 2. A cleaning material for removing oxides, scale and the like from metal surfaces formed by adding, with stirring, from around 25 to around 45 parts by volume of approximately 10% aqueous solution of sodium silicate to a mixture consisting essentially of an aqueous solution of from around 55 to around 65 parts by volume 0f hydrochloric acid (specific gravity 1.19), from around 2 to around 10 parts by volume of phosphoric acid (aqueous solution, 75% strength by weight), from around 2 to around 10 parts by volume of copper sulfate (aqueous solution, 25% strength by weight), and approximately 1% by volume of glycerine. i

3. A cleaning material for removing oxides, scale and other foreign material from metal surfaces formed by adding, with stirring, approximately 30 parts by volume of approximately 10% aqueous solution of sodium silicate to a mixture consisting essentially of an aqueous solution of approximately 60 parts by volume of hydrochloric acid (specific gravity 1.19), approximately 5 parts by volume of phosphoric acid (aqueous solution, 75% strength by weight), and approximately 5 parts by volume of copper sulfate (aqueous solution, 25% strength by weight).

4. A cleaning material for removing oxides, scale and other foreign material from metal surfaces formed by adding, with stirring, approxi-- (specific gravity 1.19) approximately 5 parts by 20 Number volume of phosphoric acid (aqueous solution,

75% strength by weight), approximately 5 parts by volume of copper sulfate (aqueous solution, 25% strength by weight), and approximately 1 by volume of glycerine.

JOHN P. BURKE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,279,101 Gravell Sept. 17, 1918 1,329,573 Allen Feb. 3, 1920 1,713,653 Gravell May 21, 1929 1,980,518 Gravell Nov. 13, 1934 2,030,601 McDonald Feb. 11, 1936 FOREIGN PATENTS Country Date 705,213 Germany Apr. 21, 1941 

4. A CLEANING MATERIAL FOR REMOVING OXIDES SCALE AND OTHER FOREIGN MATERIAL FROM METAL SURFACES FORMED BY ADDING, WITH STIRRING, APPROXIMATELY 30 PARTS BY VOLUME OF 10% AQUEOUS SOLUTION OF SODIUM SILICATE TO A MIXTURE CONSISTING ESSENTIALLY OF AN AQUEOUS SOLUTION OF APPROXIMATELY 60 PARTS BY VOLUME OF HYDROCHLORIC ACID (SPECIFIC GRAVITY 1.19), APPROXIMATELY 5 PARTS VOLUME OF PHOSPHORIC ACID (AQUEOUS SOLUTION, 75% STRENGTH BY WEIGHT), APPROXIMATELY 5 PARTS BY VOLUME OF COPER SULFATE(AQUEOUS SOLUTION, 25% STRENGTH BY WEIGTH), AND APPROXIMATELY 1% BY VOLUME OF GLYCERINE. 